Re: beaded flat plate disc

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: David Speck <dave@xxxxxxxxxxxxxxxx>

Scot,
The gas inside is most likely argon -- cheap, easily ionized, and 
inert.  The colors come from different phosphors dusted or airbrushed 
onto the beads before they are sealed.  I know that they use zinc 
sulfide for the green.  Some Calcium compounds make the orangy 
red.  Off the top of my head, I can't remember the blue phosphors, 
but none of the ones used in the toy displays are very 
expensive.   Phosphors work much better when they are doped with 
trace impurities, which cause strain in the crystal structures.  Some 
minerals are naturally doped with impurities which make for pretty 
fluorescent rocks.
In the days of color TV development, phosphor science was a closely 
held black art.  My high school physics teacher was a phosphor 
chemist for Sylvania before they closed their TV picture tube plant 
in Seneca Falls, NY.  The red phosphors were the hardest to make, but 
all the phosphors required rigorous process controls in their 
compounding, baking, and grinding.  Even a few parts per million 
difference in the dopants used could make huge differences in the 
efficiency and color of the resulting phosphor.  He said that often, 
they discarded 10 times more material than they actually used.
Dave

Tesla list wrote:

> Original poster: BunnyKiller <bunikllr@xxxxxxx>
>
> Hey All...
>
> I bought one of those 14" wide "discs" ( basically 2 plates of glass 
> with "beads" in it with a hi volt discharge in the center) to 
> produce a "flat" tesla coil streamer effect.
>
> I got it from WalMart for 20$   kinda kewl   center region is 
> green/yellow ( Im color blind so I really cant tell what color it is )
> with a red ( I was told its red) mid section and the typical blue 
> that argon produces ( that color I can see)  )  on the outer rim ( 
> obviously tinted glass or something of that nature)...   think of a 
> target for archery but wrong colors in sequence......
>
> my question is    what kind of gas is used and what is the typical 
> voltage involved in this setup?  I am going to assume argon is the 
> main constituant of the gas mix...
>
> just interested in its make-up...
> Scot D